[FlorianRappl]

Types of Changes

Prerequisites

Please make sure you can check the following two boxes:

• I have read the CONTRIBUTING document
• My code follows the code style of this project

Contribution Type

What types of changes does your code introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue, please reference the issue id)
• New feature (non-breaking change which adds functionality, make sure to open an associated issue first)
• Breaking change (fix or feature that would cause existing functionality to change)
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

Description

This pull request introduces several important improvements and fixes to the CSS engine, focusing on performance, standards compliance, and test coverage. The most significant changes include optimizing how the render tree handles inherited declarations, improving the efficiency of merging declarations, refining pseudo-element rule matching, and fixing legacy CSS hacks. The update also adds an option to control relative URL resolution in CSS and expands the test suite to cover these enhancements and fixes.